Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

909
FXUS63 KLOT 122351
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
651 PM CDT Thu Mar 12 2026

.KEY MESSAGES...

- Strong to very strong winds develop overnight tonight and
  especially Friday morning/early afternoon with peak gusts of
  50 to 60 mph during this time. High Wind Warning now in effect
  for most areas of northern IL and northwestern IN, with Wind
  Advisories across central IL and IN.

- Small potential for snow/graupel squalls with a cold front
  late tonight, mainly across far northern Illinois.

- Strong storm system may bring a threat for strong storms to
  the region on Sunday, followed by accumulating snow and
  another round of very strong winds Sunday night into Monday.

- Turning much colder early next week with Monday morning and
  Tuesday morning wind chills below zero.

&&

.DISCUSSION...
Issued at 322 PM CDT Thu Mar 12 2026

Through Friday night:

We have opted to upgrade the High Wind Watch to a warning for
tonight and Friday. In additional to the watch area, we have also
opted to include northwestern parts of IL, including the Rockford
region. A Wind Advisory remains in effect farther south across
central IL.

Confidence continues to increase that wind gusts will peak up
around (or even a bit above) 60 mph very late tonight into Friday
morning across the warned area, owing to the strength of the low
shifting into the Upper Great Lakes on Friday. A strong southerly
mass response will materialize across the region through this
evening and overnight as an impressive 70+ kt southwesterly low-
level jet develops. While we will not see wind gusts to this
magnitude at the surface, strong surface pressure falls (on the
order of ~18 mb per 6hr) overspreading the western Great Lakes in
advance of the approaching surface low will support increasingly
gusty surface winds through the night. Accordingly, we expect
southwesterly wind gusts to increase into the 45 to 50 mph range
after midnight tonight. Then, as the surface front moves across
the area into the predawn hours of Friday morning, winds will
become westerly with the cold frontal passage. Wind speeds will
peak in the 55 to 60 mph range across the warned area directly in
the wake of the front early Friday morning. Strong gusty west
winds will persist into the afternoon, but speeds should gradually
settle in the 45 to 50 mph range late in the morning and
afternoon. Wind gusts will then quickly abate with sunset Friday
evening as a progressive area of surface high pressure shifts east
across the area into early Saturday.

In addition to the strong winds, an area of showers is also
expected to develop for a period tonight along the nose of the
increasing low-level jet. The greatest chances for these (up to
~80%) continue to be across far northern IL into northwestern IN
from mid evening through early Friday morning (~9 pm through 3
am).

KJB


Saturday through Thursday:

A west-northwest flow pattern will develop across much of the
northern CONUS and Great Lakes on Saturday. A modest mid-level
shortwave trough is expected to dive across northern IL and
northwest IN and interact with a stalled baroclinic zone. While
low- level moisture looks to be a bit of a limiting factor, mid-
level moisture will be sufficient to support a couple of light
showers on Saturday (20-30% chance). With temperatures aloft
forecast to be below freezing and most of the moisture residing
in the snow growth region, it appears that any precipitation on
Saturday would fall as snow though some rain/snow mix is
possible especially during the afternoon hours. Regardless,
surface temperatures are forecast to warm into the upper 30s and
lower 40s so little to no accumulation is expected.

Heading into Saturday night, a deepening trough is expected to
begin digging into the central Plains which will lead to the
development of a strong surface low on the leeward side of the
Rockies that will then lift into northern IL and the Great Lakes
on Sunday. As the low develops the aforementioned baroclinic
zone is forecast to lift north as a warm front Saturday night.
While there is some uncertainty as to how far north the front
will get, the general consensus is for the front to stall near
the IL-WI line which would place most of northern IL and
northwest IN in the warm sector. Therefore, as the surface low
lifts towards the area the strong warm advection ahead of it
will likely lead to the development of scattered showers and
thunderstorms on Sunday, especially along and south of I-80.
Given that forecast soundings don`t show much instability (warm
air aloft likely causing a modest cap) thunder coverage will
likely be some what limited, but with the strong dynamics of the
system and the 40-50 kts of shear present a few strong to
possibly severe storms cannot be ruled out Sunday afternoon.

As the low moves into the Great Lakes Sunday evening it will
drag a strong cold front through northern IL and northwest IN
Sunday night into Monday. With temperatures forecast to quickly
cool Sunday night behind the front the rain on Sunday will
quickly transition over to snow by Monday morning. In fact,
there is even a chance (10-20%) chance for a period of freezing
rain and/or sleet Sunday night as temperatures cool but with
uncertainties in how fast temperatures cool, especially aloft,
have opted to keep a rain/snow mention in the forecast for now.
Once snow begins it is expected to prevail through the day on
Monday which will likely result in snow accumulations as
temperatures will be in the 20s through the day. That said,
there is a lot of uncertainty as to how much snow will fall due
to differences in where the deformation band on the back of the
low will develop and how deep the low will be, but latest
ensemble probabilities do have a good portion of northern IL
with at 50-60% chance of at least 2 inches of snow. Regardless
of how much snow falls, winds behind this system will be quite
strong with 35- 40+ mph gusts likely Sunday night through
Monday. Thus blowing snow is expected to develop on Monday which
will likely result in hazardous travel conditions due to
reduced visibility and snow covered roads even with lesser
accumulations.

The system and its associated snow will begin to shift east
Monday evening, but the pattern aloft will remain locked in a
northwest flow regime through the end of the week. This flow
regime will result in notably colder temperatures through the
early part of next week especially on Tuesday where highs are
forecast to be in the 20s. Additionally, this pattern will also
put in a favorable spot for clipper systems to brush the area
and bring us more chances for precipitation at times. While the
first of these periods of precipitation looks to be late Tuesday
into Wednesday, there is uncertainty of location and impacts so
stay tuned.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 651 PM CDT Thu Mar 12 2026

A strong low pressure system tracking across northern Wisconsin
will bring lowering (VFR) ceilings across the terminals through
tonight, with a period of SHRA expected overnight.

SSW winds 10 to 15 knots at TAF issuance will increase this
evening, with winds backing SSE mid to late evening before
veering SSW with gusts of 35 knots or higher by midnight/05Z.
Sporadic gusts to 40 knots are possible overnight. A cold front
will then shift winds W with frequent gusts up to 50 knots and
infrequent gusts over 50 knots Friday morning into the
afternoon. Gusts will abate late Friday afternoon, with WNW
gusts diminishing to under 20 knots by late Friday evening.

Behind the cold front, cloud depths may become sufficiently
deep for isolated SHSN with VFR to briefly MVFR visibility mid
to late Friday morning. With chances under 30 percent, did not
include a mention in the TAF at this time.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...High Wind Warning from 1 AM to 4 PM CDT Friday for ILZ003-
     ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-
     ILZ019-ILZ020-ILZ021-ILZ023-ILZ103-ILZ104-ILZ105-ILZ106-
     ILZ107-ILZ108.

     Wind Advisory from 1 AM to 6 PM CDT Friday for ILZ032-ILZ033-
     ILZ039.

IN...High Wind Warning from 1 AM to 4 PM CDT Friday for INZ001-
     INZ002-INZ010-INZ011.

     Wind Advisory from 2 AM to 7 PM EDT Friday for INZ019.

LM...Gale Warning from 10 PM this evening to 4 AM CDT Friday for
     the IL and IN nearshore waters.

     Gale Warning from 4 PM to 10 PM CDT Friday for the IL and IN
     nearshore waters.

     Storm Warning from 4 AM to 4 PM CDT Friday for the IL and IN
     nearshore waters.

&&

$$

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